Self ligating orthodontic bracket with coplanar spring

ABSTRACT

An orthodontic self-ligating bracket for orthodontic treatment of maloccluded teeth is provided that includes a bracket body and a bracket door including a coplanar spring. The bracket body has a base that is contoured to attach to a surface of a tooth, a archwire slot on the top side of the bracket body extending in a mesiodistal direction and configured to releasably retain an archwire, and a bracket groove on the top side of the bracket body extending in an occlusogingival direction towards the archwire slot. The coplanar spring includes a spring body and one or more legs that deflect in direction generally coplanar with a plane of motion of the bracket door. The one or more legs interact with one or more depressions in the bracket body to move and retain the bracket door on the bracket body.

BACKGROUND

The present invention relates generally to orthodontic brackets forproviding orthodontic treatment of maloccluded teeth, and morespecifically relates to a self-ligating orthodontic bracket with asliding door including a coplanar spring for releasably retaining anarchwire in an archwire slot.

Orthodontic brackets or braces are a very popular method of treatingmisaligned or maloccluded teeth. Traditionally, brackets are bonded tothe labial or possibly lingual surfaces of a patient's teeth, and anarchwire is placed in the slot of each bracket to guide movement of theteeth. Brackets are generally pre-adjusted to have built-inprescriptions of torque, tip, and in-out which are optimized for averagecases of tooth movement. For instance, a bracket may be angled withrespect to an occlusal plane (i.e. the bracket has a “tip angle”),depending on the tooth on which the bracket is to be placed. A ligatureor ligating module, typically an elastomeric band such as a rubber band,is placed around the tie wings of a bracket to hold the archwire inplace. However, ligatures typically cause friction on the wire duringmovement, resulting in a relatively slow treatment process, and theytend to attract plaque and trap food particles, a common cause of toothdecay or infection. As a result, the use of self-ligating orthodonticbrackets has steadily become a prevalent alternative solution tomalocclusion treatment.

A self-ligating orthodontic bracket does not require a ligature to holdthe archwire in place. Rather, the self-ligating bracket typically usesa clip or slide which opens and closes to releasably retain the archwirein the archwire slot. Thus, friction on wire movement is reducedcompared to conventional brackets, resulting in potentially fastertreatment time. An example of a conventional self-ligating bracketincludes a base for attachment to a tooth surface, an archwire slotsized for receiving an archwire, a channel formed upon the base andtransversely oriented to the archwire slot, and a sliding memberslidably retained in the channel and closeable over the archwire slot,where the sides of the bracket are crimped to securely retain thesliding member. Another type of self-ligating bracket includes aflexible pin to secure the sliding member in the closed position.However, these types of self-ligating brackets require additionalprocesses or additives for securing the sliding member to the bracket,thus adding an additional layer of manufacturing complexity andincreased cost.

Additionally, errors made while coining, bending, or crimping the sidesof the bracket to retain the sliding member are typically irreversiblewithout damaging the bracket, thus potentially resulting insignificantly higher expenditures. For example, too much compressionapplied to the sides of the bracket may preclude the sliding member frommoving, thus requiring the brackets to be discarded. Moreover, toolittle compression applied to the sides of the bracket may cause thesliding member to accidentally disengage from the bracket during use,resulting in patient and physician dissatisfaction and possible bracketrecalls.

Hence, it is desirable to facilitate the assembly process by providing aself-ligating bracket that does not require crimping, bending, coining,fastening, or gluing to assemble or adhere the sliding member to thebracket. The present invention meets this and other needs.

SUMMARY OF THE INVENTION

The self-ligating orthodontic bracket according to the present inventionprovides one or more benefits and advantages not previously offered bythe prior art, including but not limited to, a self-ligating bracketthat does not require crimping, bending, coining, fastening, or gluingto assemble or adhere the sliding member or bracket door to the bracket.Accordingly, there is provided an orthodontic self-ligating bracket fororthodontic treatment of maloccluded teeth that includes a bracket bodyhaving a bottom side and a top side, and a bracket door including acoplanar spring slidably engaged with the bracket body. The bracket bodyincludes a base on the bottom side of the bracket body that is contouredto attach to a surface of a tooth, an archwire slot on the top side ofthe bracket body extending in a mesiodistal direction and configured toreleasably retain an archwire, and a bracket groove on the top side ofthe bracket body extending in an occlusogingival direction towards thearchwire slot. The bracket door is slidably movable in the bracketgroove along a plane of motion between an open position and a closedposition. In the open position, the archwire slot is exposed to allowfor placement and removal of the archwire. In the closed position, thearchwire slot is enclosed to securely retain the archwire.

The coplanar spring includes a spring body and one or more legsconnected to the spring body that deflect in a direction generallycoplanar with the bracket door's plane of motion and that interact withone or more depressions or recesses in the bracket body. The one or moredepressions interact with the coplanar spring to provide retainingforces on the bracket door, thereby preventing disassembly of thebracket door from the bracket body.

In a preferred embodiment, the coplanar spring includes a mesial leg anda distal leg. The mesial leg of the coplanar spring includes an outermesial protrusion and an inner mesial protrusion, and the distal leg ofthe coplanar spring includes an outer distal protrusion and an innerdistal protrusion. The mesial leg and the distal leg deflect in adirection generally coplanar with the plane of motion of the bracketdoor along the bracket groove. The bracket body includes an occlusalmesial depression or recess and an occlusal distal depression or recessthat are occlusally located relative to the archwire slot, and agingival mesial depression or recess and a gingival distal depression orrecess that are gingivally located relative to the archwire slot. Theocclusal mesial depression is preferably sized to receive the outermesial protrusion of the coplanar spring, and the occlusal distaldepression is preferably sized to receive the outer distal protrusion ofthe coplanar spring. Similarly, the gingival mesial depression ispreferably sized to receive the inner mesial protrusion of the coplanarspring, and the gingival distal depression is preferably sized toreceive the inner distal protrusion of the coplanar spring.

The bracket door is slidably movable into the open position uponapplication of a force to the door such that the outer mesial protrusionand the outer distal protrusion of the coplanar spring slide into theocclusal mesial protrusion and the occlusal distal protrusion of thebracket body, respectively. Similarly, the bracket door is slidablymovable into the closed position upon application of a force to the doorsuch that the inner mesial protrusion and the inner distal protrusion ofthe coplanar spring slide into the gingival mesial protrusion and thegingival distal protrusion of the bracket body, respectively.

In a preferred aspect, the self-ligating bracket includes an open forcecontrolling member bounding the gingival mesial protrusion and thegingival distal protrusion that serves to provide opening forces on thebracket door. More particularly, the open force controlling member andgingival protrusions serve as retaining force generating features thatretain the bracket door in the closed position using a biasing force andimpose a requirement of a certain amount of force to be imposed on thecoplanar spring before the bracket door can be opened. Moreover, theocclusal mesial depression and the occlusal distal depression furtherserve to provide retaining forces on the bracket door. Morespecifically, the occlusal depressions serve as retaining forcegenerating features or indents that, upon interaction with the coplanarspring, provide retaining forces on the bracket door that retain thebracket door in the open position using a biasing force and preventaccidental disassembly of the bracket door from the bracket body.

The self-ligating bracket allows for ease of assembly of the bracketdoor to the bracket body yet relatively difficult disassembly. Inparticular, the bracket body includes tapered sides occlusally locatedrelative to the bracket groove that engage and flex the one or more legsof the coplanar spring as the bracket door is being assembled onto thebracket body and that taper off towards the one or more depressions orrecesses of the bracket body. In the preferred embodiment, the taperedsides taper off towards the occlusal mesial depression and the occlusaldistal depression. When the bracket door is slidably moved along thebracket groove towards the archwire slot, the tapered sides cause theouter mesial protrusion and outer distal protrusion to deflect until theouter protrusions reach their respective occlusal depressions, afterwhich the tension in the coplanar spring is allowed to release resultingin the bracket door being moved into the open position. Side walls ofthe occlusal depressions are cooperatively angled with respect to theouter protrusions of the coplanar spring to retain the coplanar springin the bracket body, thus preventing the coplanar spring from beingdisassembled from the bracket body.

In a preferred aspect, the bracket door includes a coplanar spring thatis integrally connected to, and inseparable from, the bracket door.Alternatively, the bracket door may include a door portion that isseparate from the coplanar spring, where the door portion and coplanarspring are assembled together to create the bracket door. Theself-ligating bracket with coplanar spring may be passive or active.

Other features and advantages of the present invention will become moreapparent from the following detailed description of the preferredembodiments in conjunction with the accompanying drawings, whichillustrate, by way of example, the operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a self-ligating orthodontic bracketaccording to a preferred embodiment of the present invention including abracket door with a coplanar spring.

FIG. 2 is an enlarged view of the encircled portion in FIG. 1 depictingone of the “stay open” retaining features that retain the bracket doorin the open position and prevent disassembly of the bracket door fromthe bracket body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides for a self-ligating orthodontic bracketthat is easier to assemble and more cost-effective than conventionalself-ligating orthodontic brackets. The present invention does notrequire crimping, bending, coining, fastening, gluing, or other similarmethods of assembling or adhering a clip or slide to a bracket, butrather uses a coplanar spring to assemble the slide to the bracket.

FIG. 1 illustrates a preferred embodiment of a self-ligating orthodonticbracket where the spring mechanism is coplanar with the bracket door. Inthis embodiment, a self-ligating bracket 10 is provided including abracket body 12 and a bracket door 14 that slidably engages with thebracket body. As illustrated in FIG. 1, the bracket body 12 includes alingual side or bottom side, a gingival side 15, a labial side or topside, and an occlusal side 16. The bottom side of the bracket body has abase (not shown) which is compound contoured to engage a surface of atooth, and an archwire slot or bracket slot 18 is positioned on the topside of the bracket body. The archwire slot extends in a mesiodistaldirection and is sized to releasably retain an archwire. Preferably, theoutside edges of the archwire slot are rounded to help prevent archwirenotching during orthodontic treatment, thus reducing the risk of fray ordamage caused by movement of the archwire within the archwire slot.Additionally, the self-ligating bracket may include curved tie winggrooves (not shown) underneath the tie wings on the occlusal side andthe gingival side of the bracket body to allow for the use of optionalligatures or other elastomerics, such as steel ligatures or powerchains, either individually or multiple simultaneously.

As illustrated in FIG. 1, the top side of the bracket body includes abracket groove 20, a mesial surface 22, and a distal surface 24. Thebracket groove extends in an occlusogingival direction and includesopposing side slots 26 which guide movement of the bracket door alongthe bracket groove. In one preferred aspect, the bracket grooveultimately connects with the archwire slot. Alternatively, a wall (notshown in the Figures) may separate the bracket groove from the archwireslot.

In this embodiment, the bracket door 14 includes a coplanar spring 28that interacts with the bracket body 14, and a door portion 30 thatslidably engages with the bracket groove 20. In the preferred embodimentdepicted in FIG. 1, the coplanar spring 28 and door portion 30 areintegrally connected to create a unitary bracket door 14. Alternatively,the coplanar spring 28 and door portion 30 may be separate componentsthat when assembled together, create the bracket door 14. In a preferredaspect, the coplanar spring 28 is metal, and the door portion 30 andbracket body 12 are made of aesthetic material, for example, ceramic.Alternatively, the entire self-ligating bracket 10 may be completelymetal, or completely made of aesthetic material such as ceramic orplastic. The door portion 30 includes opposing side edges 32complementarily received by opposing side slots 26 of the bracket groove20. The opposing side slots 26 guide and support the bracket door as thebracket door moves along a plane of motion away from and towards thearchwire slot. The bracket body thus prevents the bracket door frommoving along any other plane of motion, thereby preventing binding andreducing stress risers when the bracket door undergoes stress from thearchwire.

The coplanar spring includes a spring body 34 preferably having a mesialleg 36 and a distal leg 38. The mesial leg includes an outer mesialprotrusion 40 and an inner mesial protrusion 42, and the distal legincludes an outer distal protrusion 44 and an inner distal protrusion46. Preferably, the mesial leg and the distal leg of the coplanar springdeflect, either elastically or plastically, in a direction generallycoplanar with the plane of motion of the bracket door.

The bracket body 12 includes a plurality of depressions or recessessized to receive or engage the outer and inner protrusions of thecoplanar spring. Preferably, the bracket body includes an occlusalmesial depression or recess 48 that is sized to receive the outer mesialprotrusion 40 of the mesial leg of the coplanar spring, and an occlusaldistal depression or recess 50 that is sized to receive the outer distalprotrusion 44 of the distal leg of the coplanar spring. Additionally,the bracket body preferably includes a gingival mesial depression orrecess 52 that is sized to receive the inner mesial protrusion 42 of themesial leg of the coplanar spring, and a gingival distal depression orrecess 54 that is sized to receive the inner distal protrusion 46 of thedistal leg of the coplanar spring.

The depressions are sized to engage the inner and outer protrusions ofthe coplanar spring such that the bracket door 14 can alternate orswitch between an open position, in which the archwire slot 18 isexposed such that a user can remove or place an archwire, and a closedposition, in which the archwire slot is enclosed such that the archwireis securely retained in the archwire slot. The bracket door is slidablymovable into the open position upon application of a force to the doorsuch that the outer mesial protrusion 40 and the outer distal protrusion44 of the coplanar spring slide into the occlusal mesial depression 48and the occlusal distal depression 50, respectively. Similarly, thebracket door is slidably movable into the closed position uponapplication of a force to the door such that the inner mesial protrusion42 and the inner distal protrusion 46 of the coplanar spring slide intothe gingival mesial depression 52 and the gingival distal depression 54,respectively.

The bracket body may include points or tapered angles 56 positionedadjacent to both occlusal depressions 48 and 50. These points define thelocation where the bracket door smoothly transitions to the openposition. Moreover, the bracket body 12 includes an open forcecontrolling member 58 that bounds gingival depressions 52 and 54. Theopen force controlling member is preferably circularly or “lollipop”shaped and include radial points 60 that define the point of transitionwhere the bracket door smoothly transitions to the closed position. In apreferred aspect, the open force controlling member 58 is preferablyexposed on the labial side of the bracket body for lower profile andeasier moldability.

In one aspect, the bracket door includes an intermediate positionbetween the open and closed positions that is located between theabove-described points of transition (56 and 60). In the intermediateposition, the bracket door must be physically moved towards the pointsof transition before the bracket door can slide into either the open orclosed position. Thus, application of force is required to move thebracket door through the intermediate position before the bracket doorcan slide into either the open or closed position.

In a preferred aspect, the occlusal depressions serve to provideretaining or “stay open” forces on the bracket door. As shown in FIG. 2,as the bracket door is being moved along the bracket groove towards theopen position from the intermediate position, the outer protrusions 40and 44 of the coplanar spring engage tapered sides 62 on both the mesialand distal sides of the bracket body. The tapered sides 62 cause theouter protrusions to elastically or plastically deflect in a directiongenerally coplanar with the plane of motion of the bracket door untilthe outer protrusions reach tapered angles 56, after which the tensioncaused by the deflection of the outer protrusions is allowed to release,thus enabling the bracket door to be moved along the bracket groove tothe open position through movement of the outer protrusions of thecoplanar spring into respective occlusal depressions 48 and 50.Moreover, the occlusal depressions include side walls 64 on the mesialand distal sides of the bracket body that are cooperatively angled withrespect to the outer protrusions to prevent the outer protrusions frommoving any further in the occlusal direction. In this way, occlusaldepressions 48 and 50 serve as retaining force generating features or“stay open” features that, upon interaction with the coplanar spring,provide retaining forces on the bracket door that retain or bias thebracket door in the open position and prevent accidental disassembly ofthe bracket door from the bracket body.

Similarly, as the bracket door is being moved along the bracket groovetowards the closed position from the intermediate position, the innerprotrusions 42 and 46 of the coplanar spring elastically or plasticallydeflect in a direction generally coplanar with the plane of motion ofthe bracket door as the inner protrusions move toward radial points 60of the open force controlling member 58. Once the inner protrusions ofthe coplanar spring reach their respective radial points, the tensioncaused by the deflection of the inner protrusions is allowed to release,thus enabling the bracket door to be moved along the bracket groove tothe closed position through movement of the inner protrusions of thecoplanar spring into respective gingival depressions 52 and 54.

In another preferred aspect, the open force controlling member, incombination with the gingival depressions, serve to provide opening or“open” forces on the bracket door. When attempting to move the bracketdoor back towards the open position from the closed position, the openforce controlling member provides a force on the coplanar spring as theinner protrusions move from the gingival depressions back toward radialpoints 60. Once the inner protrusions reach radial points 60, thecoplanar spring is allowed to release its spring tension and the bracketdoor can be moved to the open position. In this way, open forcecontrolling member 58 serves as a retaining force generating featurethat not only serves to retain or bias the bracket door in the closedposition, but also imposes a requirement of a certain amount of force tobe imposed on the coplanar spring before the bracket door can be opened.

In one aspect, the self-ligating orthodontic bracket 10 may bepreassembled with the bracket door 14 operatively engaged to the bracketbody 12. Alternatively, the bracket door may be a separate component, inwhich case the bracket door can be easily assembled as subsequentlydescribed to engage with the bracket body. The bracket body 12 includestapered sides 66 positioned on both the mesial side and distal side ofthe bracket body which taper towards the bracket groove 20. Thesetapered sides engage and flex the outer protrusions of the coplanarspring as the bracket door is slidably pushed towards the occlusalmesial depression 48 and the occlusal distal depression 50, allowing foreasy assembly of the bracket door to the bracket body without the needfor adhesives or additives. Moreover, as shown in FIG. 2, occlusaldepressions 48 and 50 each include side walls 64 that are preferably,cooperatively angled to retain the coplanar spring on the bracket bodyand prevent accidental disassembly of the bracket door from the bracketbody. The self-ligating bracket 10 therefore allows for ease of assemblywhile preventing disassembly without requiring crimping, bending,coining, fastening, gluing, or other similar assembly methods which wereconventionally used in prior self-ligating brackets.

Various modifications within the scope of the preferred embodiments arepossible. For example, although the coplanar spring described above isshown as having a two legs (the mesial leg and the distal leg), eachhaving two protrusions (the occlusal protrusions and the gingivalprotrusions), a coplanar spring having a single leg with a singleprotrusion is also suitable. Thus, the coplanar spring may have just amesial leg with only an occlusal mesial protrusion, or it may have justa distal leg with only an occlusal distal protrusion, for retaining thebracket door in the open position as described above. In anotherexample, the self-ligating bracket 10 may be passive or active, theactive version of which includes an additional active spring forcontacting the archwire that may be inserted and retained in, oralternatively integral to and extending from, the spring body of thecoplanar spring.

While certain embodiments have been illustrated and described herein,those embodiments are not necessarily to be construed as advantageousover other embodiments for implementing the apparatus of the presentsubject matter. Other variations and equivalents are possible and shouldbe considered within the scope of the present subject matter.

1.-20. (canceled)
 21. A method for orthodontic treatment of maloccludedteeth, comprising: providing a bracket body having a lingual side, alabial side, a mesial side and a distal side; attaching a base on thelingual side of the bracket body to a surface of a tooth; mounting anarchwire in an archwire slot on the labial side of the bracket body, thearchwire slot extending in a mesiodistal direction and configured toreleasably retain the archwire; sliding a bracket door in a bracketgroove on the labial side of the bracket body, the bracket grooveextending in an occlusogingival direction towards the archwire slot, thebracket door sliding along a plane of motion between an open positionand a closed position, wherein the archwire slot is exposed when thebracket door is in the open position to allow for placement and removalof the archwire, and wherein the archwire slot is enclosed to securelyretain the archwire when the bracket door is in the closed position; thebracket door being biased toward the open position by a coplanar spring,the coplanar spring including a spring body, a mesial leg connected tothe spring body and a distal leg connected to the spring body, whereinthe mesial leg includes an outer mesial protrusion and an inner mesialprotrusion, wherein the distal leg includes an outer distal protrusionand an inner distal protrusion; and deflecting the mesial leg and thedistal leg in a direction generally coplanar with the plane of motion ofthe bracket door and interacting with the bracket body.
 22. The methodof claim 21, wherein the one or more occlusal depressions include anocclusal mesial depression and an occlusal distal depression, whereinthe bracket body further includes a gingival mesial depression and agingival distal depression, wherein the occlusal mesial depression issized to receive the outer mesial protrusion of the coplanar spring,wherein the occlusal distal depression is sized to receive the outerdistal protrusion of the coplanar spring, wherein the gingival mesialdepression is sized to receive the inner mesial protrusion of thecoplanar spring, and wherein the gingival distal depression is sized toreceive the inner distal protrusion of the coplanar spring; applying aforce to the bracket door to move the bracket door into the openposition so that the outer mesial protrusion and the outer distalprotrusion of the coplanar spring slide into the occlusal mesialprotrusion and the occlusal distal protrusion of the bracket body,respectively; and applying a force to the bracket door to slidably moveinto the closed position such that the inner mesial protrusion and theinner distal protrusion of the coplanar spring slide into the gingivalmesial protrusion and the gingival distal protrusion of the bracketbody, respectively.
 23. The method of claim 22, further comprising:retaining the outer mesial protrusion and the outer distal protrusion ofthe coplanar spring in the open position by providing both the occlusalmesial depression and the occlusal distal depression with a side wall.24. The method of claim 22, further comprising: slidably moving thebracket door along the bracket groove between the open position and theclosed position through an intermediate position located between taperedangles adjacent to the occlusal mesial depression and the occlusaldistal depression that define the location where bracket door moves intothe open position and radial points defining the location where thebracket door moves into the closed position.
 25. The method of claim 22,wherein the bracket body includes tapered sides occlusally located withrespect to the bracket body that engage and flex the outer mesialprotrusion and the outer distal protrusion of the coplanar spring as thebracket door is slidably moved along the bracket groove towards theocclusal mesial depression and the occlusal distal depression duringassembly of the bracket door to the bracket body.
 26. The method ofclaim 21, a door portion separate from the coplanar spring slidablyengages with the bracket groove.
 27. A method for orthodontic treatmentof maloccluded teeth, comprising: providing a bracket body having alingual side, a labial side, a mesial side and a distal side; attachinga base on the lingual side of the bracket body that is contoured toattach to a surface of a tooth; mounting an archwire in an archwire sloton the labial side of the bracket body, the archwire slot extending in amesiodistal direction and configured to releasably retain the archwire;sliding a bracket door in a bracket groove on the labial side of thebracket body, the bracket groove extending in an occlusogingivaldirection towards the archwire slot, the bracket door sliding along aplane of motion between an open position and a closed position, whereinthe archwire slot is exposed when the bracket door is in the openposition to allow for placement and removal of the archwire, and whereinthe archwire slot is enclosed to securely retain the archwire when thebracket door is in the closed position; the bracket door being biasedtoward the open position by a coplanar spring, the coplanar springincluding a spring body and one or more legs connected to the springbody, wherein the one or more legs deflect in a direction generallycoplanar with the plane of motion of the bracket door and interact withthe bracket body, wherein the one or more legs of the coplanar springinclude a mesial leg connected to the spring body and a distal legconnected to the spring body, wherein the mesial leg includes an outermesial protrusion and an inner mesial protrusion, wherein the distal legincludes an outer distal protrusion and an inner distal protrusion;deflecting the mesial leg and the distal leg in a direction generallycoplanar with the plane of motion of the bracket door; and the occlusalmesial depression and the occlusal distal depression provide retainingforces on the bracket door when in the open position, thereby preventingdisassembly of the bracket door from the bracket body.
 28. The method ofclaim 27, further comprising: retaining the outer mesial protrusion andthe outer distal protrusion of the coplanar spring when the bracket dooris in the open position by providing both the occlusal mesial depressionand the occlusal distal depression with a side wall.
 29. The method ofclaim 27, further comprising: the bracket door slidably moving along thebracket groove between the open position and the closed position throughan intermediate position located between the tapered angles adjacent tothe occlusal mesial depression and the occlusal distal depression thatdefine the location where the bracket door moves into the open positionand radial points defining the location where the bracket door movesinto the closed position.
 30. The method of claim 27, wherein thebracket body includes tapered sides occlusally located with respect tothe bracket body that engage and flex the outer mesial protrusion andthe outer distal protrusion of the coplanar spring as the bracket dooris slidably moved along the bracket groove towards an occlusal mesialdepression and an occlusal distal depression during assembly of thebracket door to the bracket body.